77RogueRunner

I'm meeting with a lady this weekend regarding some temp gauge circuitry issues. I'm trying to get all the variables down for her so she can get a more accurate picture of what is going on with the sender and gauge relationship. I'd like to know if anybody knows how hot this engine can get before bad things happen to it. What is the highest sustained operating temp? What have you seen on your scan tool? I've gotten up to 205, but that seems like it's still well within the comfort zone. I know the 7mgte's have a thermo housing with a bung for a 230* fan switch, that seems hot. I'm trying to get the gauge to read red when it's really red and not warm and trying to get norm. op. temp. in the middle (I'm calling it 198), with gauge begining to move at whatever temp as long as the two above conditions are met. Thanks....D

77RogueRunner

I'm meeting with a lady this weekend regarding some temp gauge circuitry issues for the 3.4 swap crowd. I'm trying to get all the variables down for her so she can get a more accurate picture of what is going on with the sender and gauge relationship. I'd like to know if anybody knows how hot this engine can get before bad things happen to it. What is the highest sustained operating temp? What have you seen on your scan tool? I've gotten up to 205, but that seems like it's still well within the comfort zone. I know the 7mgte's have a thermo housing with a bung for a 230* fan switch, that seems hot. I'm trying to get the gauge to read red when it's really red and not warm and trying to get norm. op. temp. in the middle (I'm calling it 198), with gauge begining to move at whatever temp as long as the two above conditions are met. Thanks....D

HighLux

Why dont you just put an aftermarket temp gauge on it temporarily and compare it to the stocker?

mt_goat

I've seen mine as high as 235 F before I got my cooling issues fixed. Now I max out at about 215-220 F, but I run waterless coolant too. The % of coolant to water you use will make a difference in how hot you can run without boiling the coolant. Once you boil you're dead. The other danger with our engines is the coolant cools the engine oil, so running hot coolant will increase the oil temp too. Same thing with ATF if you have an auto tranny, unless you have bypassed the radiator ATF cooler.


I once saw a show on ABC Primetime about Nascar racing and I caught some of the teams talking about over-heating in the pack from lack of air flow to the grill. I thought it was interesting one driver was asking the crew how hot is too hot on the water temp. He said he was running 250 degrees F. The answer came back that 280 was a blow up, 245 was too hot for power, and 235 was good. I believe those teams run the Evan's waterless coolant but I could be wrong on that.

77RogueRunner

Thanks for the info mt_goat. So these can get pretty hot, as long as they don't boil. Maybe in the 230's to err on the side of caution, 240 max....and probably for a short duration at that.

77RogueRunner

mt_goat, I forgot to ask, what was your gauge showing when you were running 235?

hross14

mine runs at 194-200 More or less. Gauge always stays in the middle. When i run the AC it actually drops a little.

There is a resistor of sorts in the gauge to make it lazy. That way people dont call toyota because their gauge is moving (WTF?? IDK).

Hook up a scanner and that will give you your real water temp.

mt_goat

The dash gauge stays in the middle though all of those temps, its about like an idiot light except it has a needle instead of a light. Frankly I'd rather have a light, it would get your attention faster.

Pikeman

The FSM says that Normal operating range for the 3.4 is 178-204 degrees. I have not been able to find anything that gives the Overheating temp or even the range for the warning gauge on the dash. Just knowing what temp the Red section starts would be good. I saw mine get up to 231 the other day and it freaked me out.

hross14

Ive seen them there before also--on a toyota race truck with a stock motor.......did it hit that temp after you shut it off or while it was driving?

If you are really worried about it---RON Davis Radiator--i think they are like $700 and cool ~30% better

forsyth793

How old or how many miles should a radiator last???